1. Field of the Invention
The invention relates, in general, to liquid filtering systems, and in particular to permanent filter systems for liquids that utilize one or more permanent filter cartridges that can be backwashed through the use of rotating high pressure sprayer assemblies, and to the ancillary equipment used with such cartridges and sprayer assemblies.
2. Description of the Related Art
Filtration systems for cleaning contaminated liquid have long been used in commercial and industrial operations where liquids, such as solvents, need to be continuously cleansed during a particular process, such as dry cleaning clothes at a professional dry cleaner. During normal operating conditions, the liquid to be filtered generally passes through a filter cartridge that is made of either disposable paper or wire mesh for collecting the contaminants, generally solids, that are suspended within the liquid. Typically, only by maintaining the level of suspended solids and other contaminants within the liquid below a certain level, can the machinery that utilizes the liquid operate properly or for its expected number of cycles. After a number of hours or cycles of running a given industrial or commercial process, the filters must be changed in order to keep the percentage of soluble soil within the liquid at a desired low level. For example, in dry cleaning operations in order to properly cleanse the clothes, it is very important to maintain a certain minimum level of purity of the dry cleaning solution in order to achieve the desired cleaning level and also to remove odors from the clothes.
Dry cleaning operations typically use Perchloroethylene combined with a small amount of surfactants and water as the liquid solvent to cleanse a variety of different types of clothing articles during a typical dry cleaning process. In conventional dry cleaning systems, the solvent is cleansed by a filter bed including a layer of paper or wire mesh material, covered with a very thin layer of diatomaceous earth which, in turn, is covered with a very thin layer of even finer activated carbon particles. This filter bed removes contaminates, which are primarily colloidally suspended solids that are washed from the clothes, and also removes various acids and odors that are dissolved in the solvent. In known filter systems, a filter assembly using replaceable cartridge filters that must be manually installed and removed from the filter assembly are utilized. The problem with servicing this type of filters are several. First, the dry cleaning system must be shut down during this filter-changing period for a fair amount of time, thus increasing downtime and decreasing overall productivity of the dry cleaning operation. Second, the disposable filters and the particulate resulting from a conventional distillation process are considered hazardous, since Perchloroethylene is listed by federal environmental regulations as a toxic substance, even at relatively low concentration levels. Accordingly, they, too, must be disposed of in a manner consistent with hazardous waste regulations. Manually changing filters not only increases exposure to these solvents, but also is messy due to the remnants of the used powdery filter bed materials which remain caked on the filters, including the very fine activated carbon powder. Thus, the necessary step of changing the disposable filter cartridge is quite unpleasant. Yet, if the operator of the dry cleaning system elects to run the dry cleaning washer when the solvent is contaminated to an unacceptable level, the clothes will not be properly cleaned. Thus, the dry cleaning operators must follow a schedule and change the filters on a regular basis, even though it is very unpleasant to do, in order to maintain quality in a dry cleaning operation.
It would be preferable to have a liquid filter cleaning system that would minimize the down time of the dry cleaning process by reducing the time required to service the filter cartridges. It would also be preferred to have a liquid filter cleaning system with a reusable filter that could be easily and repeatedly reconditioned to its original pristine state of cleanliness. In other words, it would be very desirable to be able to successfully remove all contaminants, diatomaceous earth and activated carbon from a permanent filter before beginning the next normal dry cleaning operation, which commences with the re-establishment of the filter bed, by adding fresh diatomaceous earth/activated carbon materials on a permanent filter sheet.
Some manufacturing process that employ liquids, such as solution, and the like, utilize complicated liquid-cleaning systems that not only filter out the contaminants picked up by the liquid in the process, but also distill the sludge that is created when the system's filters are backwashed. The distillation systems are generally large in size and have different types of vessels for handling the liquids or vapors. These vessels are elaborately interconnected by piping and permanently anchored to the floor or mounted to a support structure or trusses of the building. For example, in professional dry cleaning establishments, the liquid-cleaning system includes the filtering equipment, and also distillation equipment which normally includes a still (that is the reservoir in which the solvent is heated), a heating system, storage tanks, separators, condensers, various shut-off valves, motor-driven pumps and large contaminant traps, such as lint strainers. When the liquid system is down for the failure of or complex servicing of any one of these components, the entire dry cleaning operation must cease until the entire liquid-cleaning system is back to a fully operational condition. A lengthy downtime of the solvent cleaning system in a dry cleaning establishment wrecks havoc on business since all operations at the particular establishment are suspended. In order to meet commitments to customers, the clothes must be dry cleaned elsewhere and returned. Applicant hereby incorporates by reference its related U.S. Pat. No. 5,203,998.
It would, thus, be desirable to have a liquid-cleaning system that can be easily transported as a unit, and is ruggedly constructed to withstand the inevitable vibrations that occur when bulky equipment is shipped by truck. Further, it would be highly desirable to make it possible to rapidly decouple and recouple the unit to the commercial or manufacturing operation it is used with. In this way, when one or more components of the liquid-cleaning system needed service that could not be rapidly performed on-site, it would be possible to have an identical secondary liquid-cleaning system available that could be quickly interchanged with the primary liquid-cleaning system, which would then be serviced at the factory. This arrangement would permit the down time of the dry cleaning operation to be minimized when factory service or reconditioning of any portion of the liquid-cleaning system is required.
In light of the foregoing needs, one object of the present invention is to provide a liquid-cleaning system that employs a filter assembly having a permanent filter cartridge which can be reconditioned through backflushing to an original pristine state. An object of the invention is to provide a large surface area to unit volume ratio for such a permanent filter cartridge.
A related object of the present invention is to provide a rotatable sprayer nozzle assembly that fits within a permanent mesh filter cartridge and provides a plurality of high velocity jets of fluid for efficiently backflushing the mesh filter.
A further object of the present invention is to provide an arrangement for enhancing the capacity of a permanent filter system for liquids to be cleaned by using a plurality of permanent filter assemblies in parallel.
Another related object of the present invention is to provide common backwash, supply and return manifolds for processing large volumes of fluid.
Another primary object of the present invention is to provide a compact, transportable liquid-cleaning system including one or more permanent filter assemblies and a distillation system for processing spent solvent produced by backflushing dry cleaning filter beds which include diatomaceous earth and activated carbon powder.
Yet another object of an alternative form of the present invention is to provide a fluid processing center that is operable to process large volumes of contaminated solvent or other fluid by using a plurality of permanent filter assemblies that are connected in parallel to common manifolds. Such a fluid processing center can be designed to accommodate an infinite number of permanent filter assemblies each of which having a capacity to process a predetermined amount of solvent.
A related object of the alternative form of the present invention is to provide an improved fluid processing center that employs its own independent backwashable fluid circuit that is distinct from the fluid filtering circuit. Another object of this invention is to provide the operator with the capability of continuously running the filtering mode of operation while selectively backwashing a permanent filter assembly that needs to be cleaned. Such system offers tremendous economic advantages.
And finally, an object of an additional alternative form of the present invention is to provide a fluid processing center employing a plurality of filter assemblies that are connected to manifolds for processing large volumes of contaminated reusable solvent. Such a processing center should allow the operator to selectively backwash certain filter assemblies while continuously running the normal filtering mode of operation.
These and other objects, features and advantages of the present invention will become clear upon reading the following summary and detailed description of the backwashable permanent liquid filter system using rotating spray member and methods of the present invention.